Lined igniter-charge tube



'Aug. 3, 1948. T, MEISTER 2,446,187

LINED IGNITER- CHARGE TUBE Original Filed May 7, 1945 grwwwtm LEEITMela-FER,

Patented Aug. 3, 1948 LINED IGNITER-CHARGE TUBE Leo T. Meister,Hillside, N. J.

Original application May 7, 1945, Serial No.

592,433. Divided and this application September .18, 1945, Serial No.697,617

3 Claims. (or. 102-865) (Granted under the act of March 3, 1883, asamended April 30, 1928; 370 0. G. 757) The invention described hereinmay be manufactured and used by or for the Government for governmentalpurposes, without the payment to me of any royalty thereon.

The present invention relates to ammunition primers, particularly to theigniter tubes thereof.

An object of the invention is to provide an ammunition primer in whichthe igniter-charge, contained within the igniter-charge tube or body ofthe primer, is effectively sealed therein against the harmfulinfluencesof air, gases or liquids.

Another object of the invention is to provide an ammunition primer inwhich the interior liner for the igniter-charge tube is formed of afusible thin-walled metallic seamless tube closed at one end.

A further object of the invention is the provision of a primer in whichthe liner, at or near its open end, is attached to the interior wall ofthe igniting-charge tube by an air-tight connection.

A still further object is to provide the liner of a fusible materialsuch that it will intimately bond itself to the primer upon theapplication of heat.

A method of manufacturing the primer is disclosed in application SerialNo. 592,433, filed May 7, 1945, of which the present application is adivision.

Reference is made to the following description and accompanying drawingin which:

Figure 1 is a side view of a primer according to the present invention;

Figure 2 is a longitudinal central section of the primer taken on line2-2 of Figure 1;

Figure 3 is an enlarged=fragmentary central longitudinal sectional viewof the primer illustrating the joint between the liner and the ignitercharge tube; and

Figure 4 is a cross section taken through line 4-4 of Figure 1.

An igniter-charge tube 5 has at its firing end a head 6 which containsthe usual percussion elements, not shown, and is threadedly attached tothe igniter-charge tube 5 through screw threads 1 within the ignitertube 5. The threaded engagement between the tube 5 and the head 6 issufficient to effect an air-tight connection. The igniter-charge tube 5is provided with a number of vents or flame holes 8 for the passage offlame arising from the igniter-charge within the tube 5 when the primeris fired.

The igniter-charge tube 5 is advantageously made of brass and haslocated therein a thinwalled lead-tin alloy liner ID. This tube or linerIll may be formed from a disk or slug of metal by drawing operationsinvolving the use of a punch and die, more or less in the same manner ascartridge cases are drawn from disks or cups of brass. The tube or linerI0 is seamless and has a closed and. an open end. As it resembles anelongated sewing thimble having cylindricalwalls, the tube or liner I0is referred to herein and in the appended claims as thimbles.

These thimbles may be made of any easily fusible suitable metal which issubject to plastic flow in drawing and which may be cemented or solderedwithin the igniter-charge tube, as hereinafter more fully appears. Thesethimbles are advantageously formed of tin or lead, or-alloys of tin orlead, such as for example, an alloy consisting of 50% lead and 50% tin,or lead and 40% tin.

In the further description which follows, the thimbles are considered asbeing made of or drawn from an alloy consisting of 60% lead and 40% tin;it being understood, however, that the invention is not confined to theuse of this particular metal or alloy, as will be understood by theperson skilled in the art. In practice, thimbles formed of alloys oflead and tin have proved to be very satisfactory.

The thimble l0 fits closely within the interior of the igniter-chargetube 5, covering all of the flame holes 8 thereof, with the closed endportions of the thimble l0 and the tube end ll positioned adjacent eachother and the open end of thimble l0 adjacent the imperforate portion ofthe igniter tube 5 located between the screw threads 1 and the openingsnearest the said screw threads. Thimble I0 is inserted within theigniter-charge tube 5, as shown in Figure 2, and firmly pressed againstthe interior wall and closed end ll of the igniter-charge tube 5 in anysuitable manner, or as described in'thc forementioned parent applicationSerial No. 592,433.

Prior to inserting the thimble 10 into the igniter tube 5, solderingflux is applied around the thimble ill at the open end thereof. Thisflux, which is preferably a non-acid flux, extends around the thimbleand along the length thereof for a short distance, for example a quarteror a half inch, from the open end of the thimble toward its closed endas diagrammatically indicated by S in Figure 3. Thus, the soldering fluxlies between the wall of the thimble near its open end and the interiorimperforate portion of the igniter-charge tube 5.

Localized heat of suflicient intensity is applied, as suggested by theforementioned parent application Serial No. 592,433, to that area of theigniter-charge tube 5 near the open end of the thimble ID. Thecylindrical wall of the thimble melts during the heating, for anapproximate length corresponding to the distance S of Figure 3, andowing to the fact that the thimble is made of a material which is asolder, it becomes soldered --to "15118 interior wall of theignitercharge tube 5 upon cooling after the removal of the=describedheating. The soldering action extends completely around the thimble ator near the open end thereof, forming a gas-tight connection between thewalls of the thimble near its 'open end and the adjacent imperforateportions-of the igniter-charge tube 5 and the remainder of the walls ofthe thimble remain unattached to, but pressed against, the interiorwallsofthe igniter-charge tube 5.

In loading the primer, a powder charge is inserted into the thimble I0,after it has been soldered into position, and theheadfi-containing thepercussion elements, not shown, is screwed into tight engagement withthe screw threads 1. The primer is :now ready for use in connection withfixed, semi-fixed or separate loading ammunition and upon the percussionelements in the headfi being struck aflame is produced whichignites thepowder charge within the fusible srthimble Ill. The burning of thisigniter charge produces aflame which melts the fusible thimble l0andissues forth from the openings flitoignite theexplosive or propellentcharge with which the primer herein-described is-used.

:Asis'clear to those skilled in the art, the thimble lfl,-maybe formedof any metal that isreadily-fusibleby the heat or flame produced by theburning of the ig'niter charge and which can be soldered to the igniter.charge'tube 5. Arfeature contained in the embodiment of the present :inMention resides in the useof a materialfor-the thim'be Ill -whichprovides its own solder for soldering the thimble at its upper end tothe igniter-charge tube 5. In the event that the thimble lu is formed ofa metal which .does not function as a solder, or when it is-desirable to.form a soldered joint in the customary manner, the exterior walls ofthe thimble near its open .end are tinned, in a manner well known to theart, with an appropriate solder and the tinned .portioncoated with asoldering flux prior to inserting the-thimble within the igniter-chargetube Band then applying heatas explained above.

.A furtheriadvantagein using thimbles formed .wholly or in part of tin,or comprising tin as a component of the metal thereof, is thattheprodnote from the destruction of the thimble bythe burning of theigniter charge promotes or causes .de-coppering of the bore or cannon.Thimbles made of softmetals such as tin or lead, oralloys thereof, areparticularly advantageous in that ,end-of the thimble begins to melt.

they may be made slightly smaller than the interior of theigniter-charge tube 5 and stretched or expanded into position to snuglyfit against the interior wall of the igniter-charge tube 5.

This, of :course .facilitates .and insures efiective soldering finthatuponapplication of .heat, and due to the walls of the thimble nearits open end being in such close relation with the interior walls of theigniter-charge tube 5, soldering takes place practically at the instantthat the open The solder from the melting end of the thimble immediatelywets the adjacent interior walls of the ignitercharge tube 5 and uponremoval of the heat, a gas-tight joint'is formed.

I claim:

1. A primer comprising a tube having an open and a closed end with thewalls of said primer having a portion of the length thereof imperforateand the remainder of the length perforated,a thin-walled thimble ofsolder alloy in said tubehaving an open and a closed end adjacentcorresponding ends of said tube, said thimble being secured to saidtube'at theimperforate portion thereof by said solder alloy andunattached to but against, the perforated portions of said tube.

2. A primer comprising'a tube closed at one end'and having flameopeningsiin its wall, a thinwalled metallic thimble within the tube withthe closed end of the thimble adjacent the closed end 'ofv said tube,and the said thimble at lts open end being soldered to the interior Wall*of said tube.

3. A primer comprising-anigniter-charge tube closed at one end andhaving flame openings in its wall, a'thin-walledlead-tin alloy thimblewithin the said tube with the'closed end-of the thimble adjacent theclosed end of said tube, and the said thimble at its open --end beingsoldered to said tube.

LEO T. MEISTER.

REFERENCES CITED Piccard Mar. 14, 1933 Meister -Aug. 5, 1947 FOREIGNPATENTS Country Date Great Britain 1884 Number Number

